JPH07144731A - Conveyor belt - Google Patents

Abstract

PURPOSE:To provide a conveyor belt which is light weight, has high tensile force, eliminates a problem of occurrence of rust and trouble of disposal, and excels in durability. CONSTITUTION:In a conveyor belt 1 which consists of a belt-like belt main body 2 and a reinforcing layer 3 which is embedded in the belt main body 2 along its longitudinal direction, original yarns made of organic fiber having diameter of 2mm or more and less than 15mm and tensile strength of 15g/d or more are twisted together to form a yarn 3a and the yarns 3a are twisted together to form a strand 3b so as to form the reinforcing layer 3. It is formed by reinforcing cord 3A which is formed by twisting the strands 3b together and has the three-step twisting structure of lower twisting, intermediate twisting, and upper twisting.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conveyor belt, and more particularly to a conveyor belt which is lightweight, has high tension and is excellent in durability.

[0002]

2. Description of the Related Art Generally, a conveyor belt has an endless belt-shaped belt body made of rubber, a thermoplastic resin, a thermosetting resin or the like, and a longitudinal direction of the belt body for reinforcing the belt body. It is composed of a buried reinforcing layer. An example of the reinforcing material used for the reinforcing layer is an aramid woven fabric in which aramid fibers are woven. It is known that a conveyor belt using this aramid fabric is lightweight and has high tension.

On the other hand, a conveyor belt using a steel cord as a reinforcing layer is known. A plurality of steel cords are embedded in parallel along the longitudinal direction of the belt body.
It is also possible to make a conveyor belt having high tensile strength and a strength of about 10,000 kgf / cm.

[0004]

However, in the conveyor belt using the aramid fabric described above, even if the finger splice structure having the highest endless strength efficiency is applied to the endless portion (joint portion) of the conveyor belt, Since the reinforcing layer is a woven fabric, there is a limit in its bonding strength, and a woven fabric having a tensile strength of about 2000 kgf / cm is a practically usable limit. Therefore, the aramid fabric cannot be used for the conveyor belt which requires higher tension. Moreover, even if a woven fabric having a strength of more than 2000 kgf / cm can be used, it is a woven fabric,
Conveyor belts that become thicker and undergo cyclic bending fatigue are expected to have significant fatigue problems. Further, since the aramid fiber is used as a woven fabric, there is a problem that the high strength originally possessed by the aramid fiber cannot be sufficiently utilized. Further, the conveyor belt using the steel cord as the reinforcing layer has a high tensile strength, but on the other hand, has a problem that it is heavy, easily rusts, and is complicated to dispose.

The present invention was devised in view of the above-mentioned conventional problems, and is a conveyor belt which is lightweight, has high tension, is free from the problem of rusting, is not complicated to dispose, and has excellent durability. It is intended to provide.

[0006]

In order to achieve the above object, the present invention provides the above-mentioned reinforcement of a conveyor belt comprising a belt-shaped belt main body and a reinforcing layer embedded in the belt main body along its longitudinal direction. A layer has a diameter of 2 mm or more and 15 mm or less, and a tensile strength of 15 g / d or more of organic fiber raw yarns are twisted together to form a yarn, and the yarns are twisted together to form a strand, which is then twisted together. The gist of the present invention is that the reinforcing cord is formed of a lower twist, a middle twist, and an upper twist having a three-stage twisted structure.

[0007] The gist of the reinforcing cord is that it is embedded in parallel along the longitudinal direction of the belt body. Also, the twisting coefficient of the reinforcing cord is
The gist is that it is 500 to 1500.
The gist of the invention is that the number of yarns in the yarn is smaller than the number of yarns in the strand.

Further, it is a gist that the lower twist direction and the middle twist direction of the reinforcing cord are the same, and the upper twist direction is the opposite direction. Further, the gist is that the twisting directions of the reinforcing cords embedded in the belt body are arranged so that the adjacent twisting cords are in opposite directions. Further, the gist of the invention is that the embedding interval of the reinforcing cord in the belt main body is closer in both side portions than in the central portion of the belt main body.

[0009]

The present invention is configured as described above, and the reinforcing layer is
Diameter is 2mm or more and 15mm or less, and tensile strength is 15g / d
A yarn is formed by twisting the above-mentioned raw yarns of organic fibers,
This yarn is twisted to form a strand, and this strand is twisted to form a reinforcing cord.
It consists of a reinforcing cord with a three-stage twist structure of middle twist and upper twist, and since this reinforcing cord is embedded in parallel along the longitudinal direction of the belt main body, it is lightweight, has high tensile strength, and does not rust. The durability of the conveyor belt can be improved without causing any problems or the complexity of disposal.

The twisting coefficient of the reinforcing cord is 5
0 to 1500, the lower twist direction and the middle twist direction of the reinforcing cord are the same direction, and the upper twist direction is the opposite direction, or the number of yarns of the yarn is more than the number of yarns of the strand. When the number is small, the tensile strength of the reinforcing cord can be further increased, and the durability of the conveyor belt can be further improved.

Further, since the twisting directions of the reinforcing cords embedded in the belt body are opposite to each other in the adjacent reinforcing cords, meandering and curling of the reinforcing cords are prevented. The straightening property can be improved, and the reinforcing cords are embedded in the belt body more closely on both sides than on the central portion of the belt body, so that tear resistance of both sides of the conveyor belt can be improved. Is increased, and the resistance to external damage due to biting can be enhanced.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a partially cutaway perspective view of a conveyor belt according to the present invention.
Is a belt body 2 in the form of an endless belt made of rubber, a thermoplastic resin, a thermosetting resin or the like, and is embedded along the longitudinal direction of the belt body 2 to reinforce the belt body 2 as in the conventional case. The reinforcing layer 3 is integrally formed.

The reinforcing layer 3 is formed by embedding reinforcing cords 3A having a diameter of 2 mm or more and 15 mm or less in parallel along the longitudinal direction of the belt body 2 at a predetermined embedding interval.
If the diameter of the reinforcing cord 3A is less than 2 mm, the tensile strength per wire will be less than 1000 kgf, and sufficient tensile strength cannot be obtained. Therefore, in order to manufacture a conveyor belt having a tensile strength of 2000 kgf / cm or more, Since the cord must be embedded, endless processing of the joint becomes extremely complicated, and it is necessary to make it 2 mm or more from the viewpoint of productivity. If it exceeds 15 mm, high tensile strength can be obtained, but it is practically impossible to secure sufficient bonding strength at the belt endless portion, the belt durability is reduced, and the cord diameter increases, and the conveyor diameter increases. The thickness of the belt is increased and the advantage of lightness is reduced.

As shown in FIG. 2, the reinforcing cord 3A is a yarn 3a in which a plurality of original yarns of organic fibers such as aramid fibers having a tensile strength of at least 15 g / d (d: denier) or more are twisted in the same direction. A plurality of the yarns 3a are twisted again in the same direction or the opposite direction to form a strand 3b, and a plurality of the strands 3b are further twisted in the opposite direction to form a reinforcing cord 3A. , The upper twisted three-stage twisted structure. When the tensile strength of the organic fiber raw yarn is less than 15 g / d, sufficient tensile strength for the reinforcing cord 3A cannot be obtained,
The durability of the conveyor belt 1 is reduced.

Thus, the reinforcing layer 3 has a diameter of 2 mm.
The reinforcing cord 3A has a three-stage twist structure of lower twist, middle twist, and upper twist using organic fibers having a tensile strength of 15 mm or less and a tensile strength of 15 g / d or more. The reinforcing cord 3A is the belt. Since it is embedded in parallel along the longitudinal direction of the main body 2, it is lightweight and has high tensile strength, so that the durability of the conveyor belt can be improved, rust does not occur, and the used conveyor belt is discarded. The complexity of can be eliminated.

The twisting coefficient K of the reinforcing cord 3A
Is more preferably 500 to 1500. However, K
= T · D ^1/2 (T: number of times of twisting [times / 10 cm], D: total denier of reinforcing cord 3A [d]). When the twisting coefficient K is less than 500, the tensile strength of the reinforcing cord 3A is slightly improved, but the fatigue resistance is lowered and the durability of the conveyor belt 1 is lowered. When it exceeds 1500, the tensile strength and the tensile strength of the reinforcing cord 3A are reduced. Both the strength retention rate and the durability of the conveyor belt 1 are reduced.

The number of combined yarns of the yarn 3a (total number of original yarns used to form one yarn 3a) is used for forming the number of combined yarns of the strand 3b (one strand 3b). (The total number of yarns 3a). By doing this, the reinforcing cord 3A
The tensile strength can be further increased, and the durability of the conveyor belt 1 can be further improved.

The lower twist direction of the reinforcing cord (twisting direction of the original yarn) and the middle twist direction (twisting direction of the yarn 3a) are the same direction, and the upper twist direction (strand 3).
More preferably, the twisting direction of b) is the opposite direction. By doing so, the tensile strength of the reinforcing cord 3A can be further increased, and the durability of the conveyor belt 1 can be further improved.

Further, it is preferable that the reinforcing cords 3A embedded in the belt main body 2 are arranged such that the twisting directions of the reinforcing cords 3A are opposite to each other. By doing so, since the twist release torque is balanced, it is possible to prevent the conveyor belt 1 from meandering or curling, and improve the straightness of the conveyor belt.

Further, it is preferable that the reinforcing cords 3A are embedded in the belt main body 2 in both side portions more densely than in the central portion of the belt main body 2. By doing so, the tear resistance on both sides of the conveyor belt 1 is increased, and the resistance to external damage due to biting or the like can be enhanced.
The embedding interval of the reinforcing cord 3A is appropriately determined in consideration of the tensile strength required for the conveyor belt and the tensile strength of the cord used, and is not particularly limited.

Next, a description will be given of various reinforcing cords and measurement tests carried out on the conveyor belts produced by using the reinforcing cords. However, the reinforcing cord is made of aramid fiber, and Technora (manufactured by Teijin Ltd.) 150
0d raw yarn is used. Here, as the aramid fiber, those having a tensile strength of 15 g / d or more such as Kevlar manufactured by DuPont and Twaron manufactured by Akzo can be used. Further, polyarylate fiber or the like may be used. 1. Four types of reinforcing cord structures were prepared under the conditions shown in Table 1, and the tensile strength (kgf) of each reinforcing cord at this time was measured. However, the tensile test conforms to JIS L 2704. The measurement results are shown in Table 1.

[0022] As is clear from Table 1, even if the total number of denier per reinforcing cord is substantially the same, the tensile strength greatly changes depending on the structure of the reinforcing cord, and the reinforcing cord of the three-stage twisted structure of the present invention is It can be seen that the highest tensile strength is exhibited at 2450 kgf. 2. Using the above-mentioned four types of reinforcing cords, after adhesive treatment with rubber was performed, the reinforcing cords were embedded in the belt main body in parallel at predetermined intervals to produce four types of conveyor belts, respectively, and were subjected to an indoor running test. The strength retention rate (%) after running was measured. The belt running tester has the shape shown in FIG. 5, the belt running speed is 150 m / min., The pulley diameter for hanging the conveyor belt is 600 mm, and the load per reinforcing cord is 300 kgf. The traveling time of each conveyor belt is 1,500,000 times (the conveyor belt makes one rotation once). The measurement results are shown in Table 2.

[0023] As is clear from Table 2, the cord structure of the present invention has the best strength retention after running. 3. Tensile strength (kgf) of the reinforcing cord of three-stage twisted structure when changing the upper twist coefficient K, and strength retention rate (%) after running in the indoor running test of the conveyor belt at this time
Was measured. However, the test method is the same as described above. The solid line represents the tensile strength of the reinforcing cord, and the broken line represents the strength retention rate of the conveyor belt. The measurement result is shown in FIG.

As is apparent from FIG. 6, when the twisting coefficient K exceeds 1500, the tensile strength of the reinforcing cord starts to significantly decrease, the strength retention rate of the conveyor belt also decreases, and the twisting coefficient K increases. It can be seen that when the strength is less than 500, the tensile strength of the reinforcing cord is sufficiently satisfied, but the strength retention rate of the conveyor belt decreases, which adversely affects the durability of the conveyor belt. 4.3 In the reinforcing cord having a three-stage twisted structure, the twisting directions of the lower twist, the middle twist, and the upper twist were changed, and the tensile strength (kgf) was measured in the same manner as described above under the conditions of Table 3. Table 3 shows the measurement results.

[0025] As is clear from Table 3, the lower twist and the middle twist are in the same direction, and the upper twist is in the opposite direction, while the twist coefficients are all the same.
That is, SSZ changes the twist direction alternately, that is, SZ
It can be seen that higher tensile strength than S can be obtained. 5.3 In the case of a reinforcing cord having a three-stage twist structure, when the number of yarns of the yarn of the reinforcing cord is smaller than the number of yarns of the strand, and vice versa, that is, when the number of yarns of the yarn is larger than that of the strand, Based on the conditions in Table 4,
The tensile strength (kgf) and bending fatigue (times) of the reinforcing cord were measured. However, the bending fatigue measurement is based on JIS G 3535.
In accordance with, the D / d = 20 and the safety factor 10 were measured. The measurement results are shown in Table 4.

[0026] As is clear from Table 4, the reinforcing cord having a smaller number of yarns in the yarn than the number of yarns in the strand has a tensile strength higher by 30 kgf and bending fatigue more than 20,000 times, and a high tensile strength and durability. It turns out that an excellent reinforcing cord can be obtained. 6.3 Reinforcement cord with three-stage twist structure, the cord structure is 1500d / 6/27/3, the lower twist coefficient 350, the middle twist coefficient 350, the upper twist coefficient 1250, the lower twist direction and the middle twist direction are the same direction. Yes, and when a reinforcing cord having a twisted direction opposite to that of the opposite direction was prepared and its diameter was measured, it was 11 mm. Tensile strength (kgf) was measured in the same manner as above, and it was 1020.
It was 0 kgf / cm.

[0027] Note) under twist coefficient _{K L = T L · D L} 1/2 in twist coefficient _{K M = T M · D M} 1/2 T L is twist number of times (times / 10cm), D _L is twisted under The total number of denier yarns (3a in the figure). T _M is the number of times of middle twisting (turns / 10 cm), and D _M is the number of denier of the strands forming the middle twist (3b in the figure). Therefore, it can be seen that even the reinforcing cord using the aramid fiber can obtain the tensile strength substantially equal to that of the steel cord.

[0028]

The present invention is constructed as described above and the reinforcing layer has a diameter of 2 mm or more and 15 mm or less and a tensile strength of 1 or less.
5 g / d or more of organic fiber raw yarns are twisted together to form a yarn, and the yarns are twisted together to form a strand,
This strand is twisted together to form a reinforcing cord. It is composed of a lower twisted, middle twisted, and upper twisted three-tiered twisted structure, which is embedded in parallel along the longitudinal direction of the belt body. Therefore, it is lightweight, has high tension, there is no problem of rusting, and the complexity of disposal,
There is an effect that the durability of the conveyor belt can be improved.

Further, the twisting coefficient of the reinforcing cord is 5
0 to 1500, the lower twisting direction and the middle twisting direction of the reinforcing cord are the same, and the upper twisting direction is opposite, or the number of yarns in the yarn is less than the number of yarns in the strand. As a result, the tensile strength of the reinforcing cord can be further increased, and the durability of the conveyor belt can be further improved.

Further, since the twisting directions of the reinforcing cords embedded in the belt body are opposite to each other between the adjacent reinforcing cords, the meandering and curling phenomena of the conveyor belt are prevented. The straightening property can be improved, and the reinforcing cords are embedded in the belt body more closely on both sides than on the central portion of the belt body, so that tear resistance of both sides of the conveyor belt can be improved. Has the effect of increasing the resistance to external damage due to biting or the like.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view of a conveyor belt according to the present invention.

2A and 2B are explanatory views illustrating a three-stage twisted structure of a reinforcing cord, in which FIG. 2A is a side view and FIG. 2B is a sectional view.

3A and 3B are explanatory views illustrating a striking structure of a reinforcing cord, in which FIG. 3A is a side view and FIG. 3B is a sectional view.

FIG. 4 is an explanatory view illustrating a braid structure of a reinforcing cord, (a) is a side view, and (b) is a sectional view.

FIG. 5 is a schematic explanatory view of a belt running tester.

FIG. 6 is a graph showing the tensile strength of a reinforcing cord having a three-stage twisted structure when the twisting coefficient K is changed, and the strength retention rate of a conveyor belt manufactured using this reinforcing cord.

[Explanation of symbols]

 1 Conveyor Belt 2 Belt Body 3 Reinforcing Layer 3A Reinforcing Cord 3a Yarn 3b Strand

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[Procedure amendment]

[Submission date] May 27, 1994

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Claims (7)

[Claims] 1. A conveyor belt comprising a belt-shaped belt main body and a reinforcing layer embedded in the belt main body along its longitudinal direction, wherein the reinforcing layer has a diameter of 2 mm or more and 15 mm or less and a tensile strength. Yarns of 15 g / d or more of organic fiber are twisted together to form a yarn, the yarns are twisted together to form a strand, and the strands are twisted together to form a reinforcing cord. Lower twist, middle twist, upper twist A conveyor belt comprising a reinforcing cord having a three-stage twisted structure. 2. The conveyor belt according to claim 1, wherein the reinforcing cords are embedded in parallel along the longitudinal direction of the belt body. 3. The upper cord expressed as K = T · D ^1/2 where K is the twist coefficient of the reinforcing cord, T is the number of twists (10 times), and D is the total number of denier of the cord. Twist factor is 5
The conveyor belt according to claim 1, which is from 00 to 1500. 4. The conveyor belt according to claim 1, wherein the number of yarns forming the yarn is smaller than the number of yarns forming the strand. 5. The conveyor belt according to claim 1, wherein the lower twist direction and the middle twist direction of the reinforcing cord are the same, and the upper twist direction is the opposite direction. 6. The conveyor belt according to claim 1, wherein the reinforcing cords embedded in the belt main body are twisted in opposite directions to each other. 7. The conveyor belt according to claim 1, wherein the reinforcing cords are embedded in the belt main body closer to both side portions than to the central portion of the belt main body.